Objectives : To obtain basic data on blood lead level and urinary level of arsenic and cadmium of children living near a petrochemical estate and a suburban area in Ulsan, Korea and to observe the trend of the changes. In the level of these metals in these children. Methods : The study subjects comprised 626 children living near a petrochemical estate and 299 children living in a suburban area of Ulsan. We analyzed the level of lead, arsenic and cadmium using atomic absorption spectrometer. Results : The mean levels of blood lead in children living near the petrochemical estate were $5.25{mu}g/dl,;5.24{mu}g/dl,;and;7.24{mu}g/dl$, and in the years 1997, 1999, and 2000, respectively, whereas those of children living in the suburban area were $3.81{mu}g/dl,;4.75{mu}g/dl,;and;7.19{mu}g/dl$ respectively. The mean levels of urinary arsenic in children living near the petrochemical estate were $4.57{mu}g/g$ creatinine, $4.78{mu}g/g$ creatinine, and $6.02{mu}g/g$ creatinine in the year 1997, 1999, and 2000 respectively, whereas those of children living in suburban area were $2.35{mu}g/g$ creatinine, $4.75{mu}g/g$ creatinine, and $7.07{mu}g/g$ creatinine, respectively. The mean levels of urinary cadmium in children living near the petrochemical estate were $1.15{mu}g/g$ creatinine, $1.05{mu}g/g$ creatinine, and $1.71{mu}g/g$ creatinine in the year 1997, 1999, and 2000, respectively, whereas those of the children living in the suburban area were $0.74{mu}g/g$ creatinine, $1.29{mu}g/g$ creatinine, and $1.48{mu}g/g$ creatinine, respectively. There were increasing trends in the level of blood lead, urinary arsenic and cadmium of children in Ulsan, and the differences in the level of these metals were disappearing between the children living in other areas year by year. Conclusions : These results suggest that the amount of exposure to lead, arsenic, and cadmium is increasing from year to year, and there is a need for periodic biological and atmospheric monitoring of these metals in Ulsan.